Cataracts and systemic diseases

Congenital cataracts can accompany many systemic diseases in children.

The vast majority are extremely rare and are of interest to pediatric ophthalmologists. However, general ophthalmologists should be familiar with the following conditions.

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Symptoms cataracts in systemic diseases

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Metabolic diseases and cataracts

1. Galactosemia involves severe galactose absorption disorders caused by the absence of the enzyme galactose-1-phosphate uridyltransferase. Inheritance is autosomal recessive.
   • systemic disorders that appear in early childhood include growth retardation, apathy, frequent vomiting and diarrhea. Decomposition products are found in the urine after drinking milk. If galactose-containing products are not excluded from the diet, hepatosplenomegaly, kidney damage, anemia, deafness, mental retardation develop, leading to death;
   • Cataracts, characterized by central opacities in the form of "fat droplets," develop during the first days or weeks of life in most patients. Eliminating galactose (dairy products) from the diet prevents the progression of cataracts, and sometimes changes in the lens can be reversible.
2. Galactokine deficiency involves defects in the galactose chain (the first enzyme). Inheritance is autosomal recessive.
   • there are no systemic disorders, despite the presence of decay products in the urine after drinking milk;
   • Cataracts consisting of lamellar opacities may develop prenatally or after birth. Some presenile cataracts result from galactokinase deficiency. Galactose is an indirect cataractogenic agent that is the source of dulcitol (a breakdown product of galactose) within the lens. Accumulation of dulcitol in the lens increases intralenticular osmotic pressure, leading to excess water, rupture of lens fibers, and opacities.
3. Lowe syndrome (oculocerebrorenal) is a rare congenital disorder of amino acid metabolism that predominantly affects boys. Inheritance is X-linked.
   • systemic disturbances and include mental retardation, Fanconi syndrome of the proximal renal tubules, muscular hypotonia, frontal bone prominence, and sunken eyes. This is one of the few conditions in which congenital cataract and glaucoma can coexist;
   • cataract is special, the lens is small, thinned, has the shape of a disk (microphakia), posterior lentiglobus is possible. Cataract can be capsular, lamellar, nuclear or total. Carriage in women is characterized by small-point cortical opacities of the lens, usually not affecting visual acuity;
   • Congenital glaucoma occurs in 50% of cases.
4. Other disorders include hypoparathyroidism, pseudohypoparathyroidism.

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Intrauterine infections and cataracts

1. Congenital rubella is accompanied by cataracts in about 15% of cases. After the 6th week of pregnancy, the lens capsule is impermeable to the virus. Opacities of the lens (which can be either unilateral or bilateral) are most often present at birth, but can also develop after several weeks or even months. Dense pearly opacities can cover the nucleus or be diffusely located throughout the lens. The virus can persist in the lens for 3 years after birth.
2. Other intrauterine infections that may be associated with neonatal cataracts include toxoplasmosis, cytomegalovirus, herpes simplex virus, and chickenpox.

Chromosomal abnormalities and cataracts

1. Down syndrome (trisomy 21)
   • systemic disorders: mental retardation, narrow slanted eyes, epicanthus, flat face with characteristic prognathism, brachycephaly with a flattened occiput, wide palms and short arms, protruding tongue;
   • Cataracts of various morphologies occur in approximately 5% of patients. Opacities are usually symmetrical and often develop in late childhood.
2. Other chromosomal abnormalities associated with cataracts include Patau syndrome (trisomy 13) and Edward syndrome (trisomy 18).
3. Hallermann-Streiff-Francois syndrome is a rare disorder.
   • systemic disorders: prominent forehead, small "bird nose", baldness, micrognathia and pointed chin, short stature and hypodontia;
   • Cataracts, which may be membranous, are found in 90% of cases.
4. Nance-Horan syndrome has an X-linked inheritance pattern.
   • systemic disorders: additional incisors, protruding, forward-turned ears, small metacarpal bones;
   • The cataract may be dense with mild microphthalmos. Female carriers may have subtle opacities in the suture area.

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Diagnostics cataracts in systemic diseases

In the neonatal period, it is impossible to determine visual acuity, therefore it is necessary to assess the density and morphology of opacities, other associated eye symptoms and the child's visual behavior, and to determine the degree of influence of cataracts on vision.

Density and possible impact on visual functions are assessed based on the appearance of a reflex from the fundus and the degree of its visualization during direct and indirect ophthalmoscopy. Examination of newborns has been simplified with the introduction of high-quality portable slit lamps. A detailed assessment of the anterior segment is possible when the child's head movements are limited. Ophthalmoscopically, cataract density is divided into:

• A very dense cataract that covers the pupil and makes it impossible to examine the fundus; the decision to operate is clear.
• Less dense cataracts, in which the retinal vessels can only be examined by indirect ophthalmoscopy. Other characteristics include central or posterior capsular opacities greater than 3 mm in diameter.
• Minor opacities in which the retinal vessels can be visualized by direct and indirect ophthalmoscopy. Other characteristics include central opacities less than 3 mm in diameter and peripheral, anterior capsular, or punctate opacities that extend into the clear zones of the lens.

The morphology of the opacities is key in determining the etiology, as described previously.

Associated ocular pathology may involve the anterior segment (corneal opacities, microphthalmos, glaucoma, persistent hyperplastic primary vitreous) or posterior segment (chorioretinitis, Leber amaurosis, rubella retinopathy, foveal or optic nerve hypoplasia). Examination under general anesthesia and a series of repeat examinations are necessary to assess the progression of the cataract or associated disease.

Other indicators of significant vision loss include lack of central fixation, nystagmus, and strabismus. Nystagmus carries a poor vision prognosis.

Specialized tests and visual evoked potentials provide additional useful information, but they should not be used alone.

Systemic examination

When establishing the hereditary nature of cataracts, the examination complex of a newborn with a bilateral process should include the following:

1. Serological tests for intrauterine infection (TORCH - toxoplasmosis, rubella, cytomegalovirus and herpes simplex). If the anamnesis included a rash during pregnancy, titration of antibodies against chickenpox and herpes zoster is indicated.
2. Urine. Urine analysis for decreased galactose content after milk consumption (galactosemia) and chromatography for amino acids (Lowe syndrome).
3. Other studies: detection of excess blood glucose, serum calcium and phosphorus, galactose-1-phosphate uridyltransferase and galactokinase in erythrocytes.
4. Referral to a pediatrician is warranted in cases of dysmorphism or suspicion of other systemic diseases. In such cases, chromosome analysis may be useful.

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Treatment cataracts in systemic diseases

Determining the timing of the operation is an important step, and the following should be taken into account:

1. Bilateral dense cataracts require early intervention (within 6 weeks of birth) to avoid the development of amblyopia. If the opacities are asymmetrical, the worse eye is operated on first.
2. Bilateral partial cataracts do not require surgery if they are stable. In case of doubt, it is reasonable to delay surgery and monitor opacities and visual function; intervention is indicated if visual impairment is detected.
3. Unilateral dense cataract requires urgent surgery (within a few days) followed by active treatment of amblyopia, but even despite this, the results are disappointing. If cataract is detected 16 weeks after birth, surgery is inappropriate due to irreversible amblyopia.
4. Unilateral partial cataracts usually do not require surgery. Pupil dilation and contralateral patching of the eye are recommended to prevent amblyopia.

It is important to correct the accompanying abnormal refraction.

Technique of operation

1. A 6 mm wide scleral tunnel is formed.
2. The keratome is inserted into the anterior chamber (usually 3 mm wide) and filled with viscoelastic.
3. Anterior capsulorhexis is performed. In children, the anterior capsule is more elastic than in adults, which complicates the capsulorhexis process.
4. The remaining lens is aspirated using a vitreotome or a Simcoe cannula.
5. Then a capsulorhexis is performed on the posterior capsule.
6. Partial anterior vitrectomy is performed.
7. If necessary, a posterior chamber intraocular lens made of PMMA is implanted into the capsular bag.
8. For patients with associated hyperplastic primary vitreous, microsurgical scissors and tweezers may be required to remove dense capsular material or retrolenticular opacities. Occasionally, intraocular bipolar cauterization of bleeding vessels may be necessary.
9. If the scleral tunnel is successfully formed, no suturing is required.

Cataract surgery in children

Cataract surgery in children is associated with more frequent complications" than in adults.

1. Posterior capsule opacification is quite common if the capsule is preserved. It is most significant in young children due to the risk of amblyopia. If anterior vitrectomy is not performed, anterior vitreous opacification may occur regardless of the capsulorhexis performed. The likelihood of opacification is lower with combined posterior capsulorhexis and vitrectomy.
2. Secondary films form across the pupil, especially in eyes with microphthalmos or concomitant chronic uveitis. If postoperative fibrinous uveitis is not treated vigorously enough, the film is likely to form. Delicate films are dissected with the NchYAG laser; if they are denser, surgery is required.
3. Proliferation of the lens epithelium is common but usually does not affect vision if it is located outside the optic ossicle. It is encapsulated between the remnants of the anterior and posterior capsules and is known as the Soemrnerring ring.
4. Glaucoma may develop over time in about 20% of cases.
   • Closed-angle glaucoma may occur immediately after surgery in eyes with microphthalmos as a result of pupillary block.
   • Secondary open-angle glaucoma may develop years after surgery, so continuous monitoring of intraocular pressure for several years is very important.
5. Retinal detachment is rare and is considered a late complication.

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Carrying out surgery on newborns and young children

At present, the difficulties associated with the technique of performing cataract surgery in neonates and young children have been largely resolved, but the results on vision remain disappointing due to the rapid development of amblyopia and its irreversibility. In relation to optical correction of aphakic eyes in children, two factors are taken into account - age and laterality of aphakia.

1. Glasses are prescribed to older children with bilateral aphakia, but not to monolateral aphakia (due to possible anisometropia and aniseikonia). Glasses are uncomfortable for newborns with bilateral aphakia due to their weight, discomfort, prismatic distortion, and narrowing of the visual field.
2. Contact lenses provide the best visual results for both mono- and bilateral aphakia. In children over 2 years of age, problems and inconveniences arise when wearing them, as the child becomes active and independent. The contact lens may be displaced or lost, which increases the risk of developing amblyopia. In bilateral aphakia, the solution is to prescribe glasses, while in monolateral aphakia, it is more appropriate to implant an intraocular lens.
3. Intraocular lens implantation is increasingly used in small children and even newborns, and in certain cases it is quite effective and safe. Knowledge of the degree of the moptic shift that occurs in the developing eye, in combination with accurate biometry, allows the power of the intraocular lens to be calculated taking into account primary hyperopia (corrected with glasses), and with age, the refraction approaches emmetropic. However, the final refraction varies and it is impossible to guarantee emmetropia in older age.
4. Patching the eye to treat or prevent amblyopia is ineffective.